Bug#659762: lvm2: LVM commands freeze after snapshot delete fails

[Frederic Van Espen]

We are seeing this as well on a build server where the LVM volumes are
managed by sbuild. Randomly the snapshots cannot be removed by sbuild
when the build is done and all the lv* commands hang forever. This
happens several times per day so it is quite easily reproducible

The only way around this is to reboot and then manually remove them.

Attached is some output I see when I increase verbosity on schroot.
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E: 05lvm:     Using logical volume(s) on command line
E: 05lvm:     Archiving volume group "main" metadata (seqno 333).
E: 05lvm:     Removing snapshot baseline2-61c813e3-f1d7-4bd9-b9c7-0d3f85e8b4de
E: 05lvm:     Found volume group "main"
E: 05lvm:     Found volume group "main"
E: 05lvm:     Loading main-baseline2_i386_chroot table (253:1)
E: 05lvm:     Loading main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de table (253:5)
E: 05lvm:     main/snapshot0 already not monitored.
E: 05lvm:     Suspending main-baseline2_i386_chroot (253:1) with device flush
E: 05lvm:     Suspending main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de (253:5) with device flush
E: 05lvm:     Suspending main-baseline2_i386_chroot-real (253:6) with device flush
E: 05lvm:     Suspending main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de-cow (253:7) with device flush
E: 05lvm:     Found volume group "main"
E: 05lvm:     Resuming main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de-cow (253:7)
E: 05lvm:     Resuming main-baseline2_i386_chroot-real (253:6)
E: 05lvm:     Resuming main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de (253:5)
E: 05lvm:     Removing main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de-cow (253:7)device-mapper: remove ioctl on  failed: Device or resource busyUnable to deactivate main-baseline2--61c813e3--f1d7--4bd9--b9c7--0d3f85e8b4de-cow (253:7)Failed to resume baseline2-61c813e3-f1d7-4bd9-b9c7-0d3f85e8b4de.libdevmapper exiting with 1 device(s) still suspended.